The piperazines are a broad class of chemical compounds, many with important pharmacological properties, which contain a core piperazine functional group. Many currently notable pharmaceutical drugs contain a piperazine ring as part of their molecular structure. Examples include: antianginals (ranolazine, trimetazidine); antidepressants (amoxapine, befuraline, buspirone, flesinoxan, gepirone, ipsapirone, nefazodone, piberaline, tandospirone, trazodone, vilazodone, zalospirone); antihistamines (buclizine, meclozine, cinnarizine, cyclizine, hydroxyzine, cetirizine, levocetirizine, niaprazine); antipsychotics (fluphenazine, perphenazine, trifluoperazine, prochlorperazine, thiothixene, flupentixol, zuclopenthixol, amperozide, aripiprazole, lurasidone, clozapine, olanzapine, perospirone, ziprasidone); urologicals (sildenafil, vardenafil).
Piperidine is also widely used building block and chemical reagent in the synthesis of organic compounds, including pharmaceuticals. Similar to piperazine, piperidine and its derivatives are ubiquitous building blocks in the synthesis of pharmaceuticals and fine chemicals. For example, the piperidine structure is found in the following classes of pharmaceuticals: SSRI (selective serotonin reuptake inhibitors) (paroxetine); analeptics/nootropics (stimulants) (methylphenidate, ethylphenidate, pipradrol, desoxypipradrol); SERM (selective estrogen receptor modulators) (raloxifene); vasodilators (minoxidil); neuroleptics (antipsychotics) (risperidone, thioridazine, haloperidol, droperidol, mesoridazine); opioids (pethidine, meperidine, loperamide).
Considering their prevalence in the formation of a variety of important pharmaceutical compounds, there is a need for new and improved processes for making both piperazine and piperidine compounds, including intermediates and derivatives thereof, that minimizes the formation of unwanted by-products and eliminates the need for additional purification steps where product is lost.